1. Field of the Invention
Embodiments of the present invention relate to a liquid discharge head and an image forming apparatus.
2. Description of the Related Art
As an image forming apparatus, such as a printer, a facsimile machine, a copier, a plotter, and a multifunctional peripheral thereof, a liquid discharge recording type image forming apparatus has been known. In the liquid discharge recording type image forming apparatus, such as an inkjet recording apparatus, a recording head including a liquid discharge head (a droplet discharge head) is utilized.
Such an image forming apparatus usually includes a recovering mechanism. The recovering mechanism removes residual ink and adhering substances by wiping a surface of a nozzle plate (a nozzle surface) of a liquid discharge head.
In order to protect side surfaces of a nozzle plate and a flow channel member from penetration of ink or from physical contact from outside, a nozzle cover (a nozzle protection member) may be attached to a liquid discharge head.
For some liquid discharge heads, a frame member that forms an outer circumferential surface of a head is utilized as a nozzle plate protection member. In this case, in order to reduce the cost for components, individual nozzle covers are not provided.
For example, a liquid discharge head has been known such that a portion of a frame member covers a peripheral portion of a bounded surface of a nozzle plate of a flow channel plate. The liquid discharge head has a configuration such that an outer circumferential surface of the nozzle plate faces an internal circumference of a peripheral portion of an opening of a frame member (cf. Patent Document 1). As another example, a liquid discharge head has been known such that slit-shaped openings are formed in an outer periphery surface of a frame member, and protruding portions which have been formed at corresponding four sides of a nozzle plate are inserted into the slit-shaped openings. In the liquid discharge head, the frame member functions as a protection member for protecting the nozzle plate (cf. Patent Document 2).
Further, a liquid discharge head has been known such that the liquid discharge head includes a housing that covers a side surface of a head chip. In the liquid discharge head, a sealing member or the housing is made molten and adhered to the side surface of the head chip, thereby filling a gap between the side surface of the head chip and the housing (cf. Patent Document 3).
Patent Document 1: Japanese Patent Laid-Open Application No. 2006-51746
Patent Document 2: Japanese Patent Laid-Open Application No. 2009-214303
Patent Document 3: Japanese Patent Laid-Open Application No. H09-66607
However, in the configuration disclosed in Patent Document 1, the outer circumferential surface of the nozzle plate is not joined to the internal circumference of the peripheral portion of the opening of the frame member. In this case, a gap may occur between the outer circumferential surface of the nozzle plate and the internal circumference of the peripheral portion of the opening of the frame member. Therefore, there is a problem such that a liquid (waste liquid) that is removed by the wiping operation penetrates the gap, and thereby the waste liquid accumulates on the nozzle surface.
Further, in the configuration disclosed in Patent Document 2, since the protruding portions of the nozzle plate are inserted into the slit-shaped openings, a gap and a level difference may occur between the nozzle surface and a portion covered with the frame member. In this case, the portion having the level difference may be filled with a sealant. However, in general, water-repellent processing has been performed on the nozzle surface. Therefore, adhesiveness between the sealant and the nozzle surface is weakened with time, and it is possible that a gap occurs between the frame member and the nozzle surface. Accordingly, similar to the case of Patent Document 1, there is a problem such that a liquid (waste liquid) removed by the wiping operation penetrates into the gap, and the waste liquid is accumulated on the nozzle surface.
Further, in the configuration disclosed in Patent Document 3, the joining portion between the head chip and the housing is on the side of the head chip. Therefore, there is a problem that a peripheral portion of the nozzle plate may not be protected.